Dose equivalent is defined as the product of the absorbed dose in tissue, the quality factor, and other modifying factors.

• A. The product of the absorbed dose in tissue, the quality factor, and other modifying factors.
• B. The energy imparted per unit mass of irradiated material.
• C. The number of decays per second.
• D. Exposure in air.

Answer: (A)

Dose equivalent expresses potential biological harm by adjusting the energy deposited in tissue for how damaging the radiation type is. Absorbed dose tells you how much energy per unit mass is deposited (gray). But different radiations cause different biological effects for the same energy, so the quality factor (and any additional modifiers) scales that energy to reflect expected harm. Multiplying the absorbed dose by the quality factor and these modifiers gives dose equivalent (units of sieverts), which lets us compare risks across radiation types. The other statements describe different quantities: energy imparted per unit mass is the absorbed dose, the number of decays per second is activity, and exposure in air is an older, separate measure.